The present invention relates to an arrangement on packing machines for the feeding out of flattened, tubular blanks from a stack magazine, this arrangement comprising a reciprocating driving element.
In packing machines for the manufacture of non-returnable packages of the so-called gable-top type, use is made in general of prefabricated tubular packing container blanks. The blanks which are manufactured from a laminated material comprising layers of paper and thermoplastics are provided with a number of wall panels divided by means of vertical crease lines, and can be laid flat therefore in a simple manner during handling and storage. In the packing machine the blanks in flattened condition are placed manually or automatically into a stack magazine, from which they are removed one by one in order to be raised to a square cross-sectional shape and subsequently be processed and converted to filled and closed packing containers.
Since the laminated packing material is relatively rigid, the flattened blanks have a tendency to open a little so that panels lying against each other do not rest on top of one another (so-called spring-back). This means in other words that the total thickness of the individual blanks when they are placed into the magazine may vary on the one hand owing to individual differences, and on the other hand because of the pressure exercised by the blanks lying on top. As the blanks are fed out one at a time from the lower end of the magazine the varying thickness of the blanks causes great difficulties, especially in cases of the feeding-out arrangement generally used up to now, where a slot or opening of limited height is made use of in order to restrict the feeding out to an individual packing container blank at a time. This type of feeding-out arrangement is shown in Swedish patent application 8301122-1, and it is the purpose of the present invention, in principle, to provide an improvement of this feeding out arrangement.